JP2018095397A - Sheet conveying device and image forming apparatus equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device equipped with a conveying belt in which a poor adhesion of a sheet to the conveying belt is inhibited from being caused and in which the sheet is excellent in a characteristic of conveyance by the conveying belt, and an image forming apparatus equipped with the same.SOLUTION: A sheet conveying device 40 comprises a conveying belt 41 for conveying a sheet S to a predetermined sheet conveying direction A on a first surface 411, an air blowing part 44, and a suction part 43. The air blowing part 44 blows air toward the sheet S at an upstream side in the sheet conveying direction A of an image forming part 50 to bring the sheet S into tight contact with the first surface 411 of the conveying belt 41. The suction part 43 generates a negative pressure between the sheet S brought into tight contact with the first surface 411 by the air blowing part 44 and the conveying belt 41 to thereby bring the sheet S into tight contact with the first surface 411 of the conveying belt 41.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a sheet conveying apparatus including a conveying belt that conveys a sheet, and an image forming apparatus including the sheet conveying apparatus.

  An image forming apparatus such as a printer, a copier, or a facsimile includes a sheet feeding unit that feeds a sheet, a sheet conveying device that conveys a sheet fed by the sheet feeding unit, and a sheet conveyed by the sheet conveying device And an image forming unit for forming an image.

  As a sheet conveying apparatus that conveys a sheet to an image forming unit, a conveying apparatus that includes a conveying belt that conveys a sheet and a suction unit is known (for example, see Patent Document 1). In this sheet transport apparatus, the suction unit generates a suction force between the sheet and the transport belt, whereby the sheet is brought into close contact with the transport belt, and the sheet is transported by the transport belt in such a close contact state.

JP 2008-222418 A

  By the way, the sheet that has been fed by the sheet feeding unit and has reached the conveying belt of the sheet conveying apparatus may have a deformation such as undulation at the leading end thereof. When the leading edge of the sheet is deformed in this manner, a gap is likely to be generated between the leading edge of the sheet and the conveyance belt. For this reason, poor adhesion of the sheet to the conveyance belt is likely to occur, and there is a possibility of deteriorating the conveyance characteristics of the sheet by the conveyance belt. When the sheet conveyance characteristics of the conveyance belt are deteriorated, an image defect occurs in an image formed by the image forming unit.

  The present invention has been made in view of such circumstances, and an object of the present invention is to suppress the occurrence of poor adhesion of the sheet to the conveyance belt in the sheet conveyance apparatus including the conveyance belt, and An object of the present invention is to provide a sheet conveying apparatus having excellent sheet conveying characteristics and an image forming apparatus having the sheet conveying apparatus.

  A sheet conveying apparatus according to one aspect of the present invention is a sheet conveying apparatus that conveys a sheet to a predetermined processing unit, and includes a first surface and a second surface opposite to the first surface, A conveying belt that is disposed to face the processing unit and conveys the sheet in a predetermined conveying direction on the first surface, and blows wind toward the sheet on the upstream side in the conveying direction of the processing unit. An air blowing unit for bringing the sheet into close contact with the first surface of the transport belt; and the sheet disposed opposite to the processing unit via the transport belt and in close contact with the first surface by the air blowing unit; A suction unit that causes the sheet to be in close contact with the first surface of the transport belt by generating a negative pressure between the transport belt and the transport belt.

  According to this sheet conveying apparatus, the sheet is brought into close contact with the conveying belt by the negative pressure by the suction unit while the sheet is brought into close contact with the conveying belt by the wind blown from the blower. That is, the air blown from the blower unit can assist the adhesion of the sheet to the conveyance belt by the suction unit. For this reason, even when deformation such as undulation is generated at the leading edge of the sheet, it is possible to prevent a gap from being generated between the leading edge of the sheet and the conveying belt, and the adhesion of the sheet to the conveying belt is poor. Can be prevented. Therefore, it is possible to provide a sheet conveying apparatus having excellent sheet conveying characteristics by the conveying belt.

  In the sheet conveying apparatus, the air blowing unit includes a blower duct that extends in a width direction of the transport belt and includes a blower outlet that blows air toward the sheet, and the blower duct blows out from the blower outlet. It is good also as a structure which has a wind direction adjustment part which spreads the wind to be made toward the both ends from the said width direction center part.

  In this aspect, the wind direction adjusting unit adjusts so that the wind blown from the blower outlet of the blower duct spreads from the center in the width direction of the conveying belt toward both ends. Accordingly, the sheet can be uniformly adhered in the width direction of the conveyance belt. Accordingly, it is possible to further improve the sheet conveyance characteristics of the conveyance belt.

  In the sheet conveying apparatus, the wind direction adjusting unit includes a plurality of wind direction adjusting plates arranged in parallel in the width direction, which divides the air outlet into a plurality of regions arranged in the width direction, and the plurality of wind directions. The adjustment plate may be configured to be inclined toward the end portion from the central portion in the width direction and extend toward the lower side approaching the first surface.

  In this aspect, the wind direction adjusting unit can be realized with a simple configuration in which a plurality of wind direction adjusting plates are arranged in parallel in the width direction of the conveyance belt.

  In the sheet conveying apparatus, the wind direction adjusting unit may include a shielding unit that shields the blowing of wind from the air outlet to the central portion in the width direction.

  In this aspect, the blowout of the wind from the outlet of the air duct to the center in the width direction of the conveyor belt is shielded by the shielding part. Thereby, the wind which blows off from the blower outlet of a ventilation duct spreads more reliably toward the both ends from the width direction center part of a conveyance belt. For this reason, a sheet | seat can be closely_contact | adhered uniformly in the width direction of a conveyance belt.

  In the sheet conveying apparatus, the conveying belt has a plurality of through holes penetrating from the first surface to the second surface, and the suction portion is disposed to face the second surface of the conveying belt. Further, the negative pressure may be generated by sucking air through the through hole, and the sheet may be in close contact with the first surface of the transport belt.

  In this aspect, the suction unit is configured to adhere the sheet to the transport belt by sucking air through the through hole of the transport belt. On the other hand, as described above, the air blown from the blower unit toward the conveyance belt can assist the adhesion of the sheet to the conveyance belt by the suction unit. For this reason, the selection range of the air suction capability in the suction portion can be expanded, and for example, a general-purpose suction fan having a relatively low air suction capability (low maximum static pressure) can be used as the suction portion. .

  An image forming apparatus according to another aspect of the present invention includes the above-described sheet conveying device, and an image forming unit as the processing unit that forms an image on a sheet conveyed by the conveying belt of the sheet conveying device. Prepare.

  According to this image forming apparatus, since the above-described sheet conveying apparatus having excellent sheet conveying characteristics by the conveying belt is provided, an image formed by the image forming unit has an image defect due to a sheet conveying defect. It is suppressed from occurring.

  According to the present invention, it is possible to assist the close contact of the sheet to the transport belt by the suction unit with the air blown from the blower toward the transport belt, and to suppress the occurrence of poor contact. Accordingly, it is possible to provide a sheet conveying apparatus having excellent sheet conveying characteristics by the conveying belt, and an image forming apparatus including the sheet conveying apparatus.

1 is a diagram schematically illustrating an image forming apparatus including a sheet conveying device according to an embodiment of the present invention. FIG. 3 is an enlarged perspective view illustrating the vicinity of a sheet conveying device and an image forming unit. FIG. 3 is a perspective view of a state in which the sheet conveying device and the image forming unit in FIG. 2 are cut along line III-III. FIG. 3 is a cross-sectional view of the vicinity of a sheet conveying device and an image forming unit. FIG. 6 is a perspective view for explaining a configuration of a conveyance belt and a belt guide member of a suction unit provided in the sheet conveyance device. FIG. 6 is a perspective view of a state in which the conveyance belt and the belt guide member of FIG. 5 are cut along a VI-VI line. It is a perspective view which expands and shows a part of FIG. It is the figure which looked at the suction part with which a sheet conveying device is equipped from the upper part. It is a figure for demonstrating the structure of the ventilation duct in the ventilation part with which a sheet conveying apparatus is equipped, and is the perspective view of the state cut | disconnected by the IX-IX line of FIG. It is a figure for demonstrating the structure of a ventilation duct, and is a perspective view of the state cut | disconnected by the XX line of FIG.

  Hereinafter, a sheet conveying apparatus and an image forming apparatus according to an embodiment of the present disclosure will be described with reference to the drawings. In the following, the directional relationship will be described using XYZ orthogonal coordinate axes. X direction corresponds to the front-rear direction (+ X is back, -X is front), Y direction is left-right direction (+ Y is left, -Y is right), and Z direction is up-down direction (+ Z is up, -Z is down) To do. In the following description, the term “sheet” means copy paper, coated paper, OHP sheet, cardboard, postcard, tracing paper, other sheet material subjected to image forming processing, or any processing other than image forming processing. Means the sheet material to receive.

[Entire configuration of image forming apparatus]
FIG. 1 is a diagram schematically illustrating an image forming apparatus 1 including a sheet conveying device 40 according to an embodiment of the present invention. An image forming apparatus 1 shown in FIG. 1 is an ink jet recording apparatus that forms (records) an image on a sheet S by ejecting ink droplets. The image forming apparatus 1 includes an apparatus main body 10, a paper feeding unit 20, a guide unit 30, a sheet conveying device 40, an image forming unit 50, and a paper discharge tray 60 as a paper discharge unit.

  The apparatus main body 10 is a box-shaped housing that houses various apparatuses for forming an image on the sheet S. The apparatus main body 10 is formed with a first conveyance path 11, a second conveyance path 12, and a third conveyance path 13 that are conveyance paths for the sheet S.

  The paper feeding unit 20 feeds the sheet S to the first transport path 11. The paper feed unit 20 includes a paper feed cassette 21 and a pickup roller 22. The paper feed cassette 21 is detachable from the apparatus main body 10 and accommodates the sheet S therein. The pickup roller 22 is disposed on the −Y side (right side) and the + Z side (upper side) end of the paper feed cassette 21. The pickup roller 22 takes out the sheets S one by one from the paper feed cassette 21 and sends them out to the first conveyance path 11.

  The sheet S fed to the first transport path 11 is transported toward the registration roller pair 112 by the first transport roller pair 111 provided in the first transport path 11. The registration roller pair 112 has a function of correcting the oblique conveyance of the sheet S. Thereby, the position of the image formed on the sheet S is adjusted. The registration roller pair 112 sends the sheet S toward the sheet conveying device 40 via the guide unit 30 in accordance with the timing of the image forming process by the image forming unit 50.

  The guide unit 30 guides the sheet S sent by the registration roller pair 112 toward the first surface 411 of the transport belt 41 in the sheet transport apparatus 40.

  When the leading end of the sheet S guided by the guide unit 30 comes into contact with the first surface 411 of the conveying belt 41, the sheet S is conveyed in the sheet conveying direction A while being held on the first surface 411 by driving the conveying belt 41. Is done. The sheet conveying direction A is a direction from the −Y side (right side) to the + Y side (left side) in the Y direction (left and right direction). A detailed configuration of the sheet conveying apparatus 40 will be described later.

  An image forming unit 50 is disposed on the + Z side (upper side) of the sheet conveying apparatus 40. Specifically, the image forming unit 50 is disposed on the + Z side (upper side) of the sheet conveying apparatus 40 so as to face the first surface 411 of the conveying belt 41. The image forming unit 50 functions as a processing unit that performs a predetermined process on the sheet S. The image forming unit 50 is formed on the sheet S conveyed in the sheet conveying direction A while being held on the first surface 411 of the conveying belt 41. An image is formed by performing an image forming process. In the present embodiment, the image forming unit 50 forms an image on the sheet S by ejecting ink droplets using an ink jet method.

  The image forming unit 50 will be described with reference to FIGS. 2 to 4 in addition to FIG. FIG. 2 is an enlarged perspective view showing the vicinity of the sheet conveying apparatus 40 and the image forming unit 50. FIG. 3 is a perspective view of the sheet conveying device 40 and the image forming unit 50 of FIG. 2 taken along the line III-III. FIG. 4 is a cross-sectional view of the vicinity of the sheet conveying device 40 and the image forming unit 50.

  The image forming unit 50 includes line heads 51Bk, 51C, 51M, and 51Y. The line head 51Bk ejects black ink drops, the line head 51C ejects cyan ink drops, the line head 51M ejects magenta ink drops, and the line head 51Y ejects yellow ink drops. To do. The line heads 51Bk, 51C, 51M, and 51Y are arranged in parallel from the upstream side in the sheet conveying direction A toward the downstream side. Since the line heads 51Bk, 51C, 51M, and 51Y have the same configuration except that the colors of the ink droplets to be ejected are different, they may be collectively referred to as the line head 51.

  The line head 51 forms an image on the sheet S by ejecting ink droplets onto the sheet S conveyed in the sheet conveying direction A while being held on the first surface 411 of the conveying belt 41. Specifically, the line head 51 ejects ink droplets toward the sheet S that is transported by the transport belt 41 and passes through a position facing the line head 51. Thereby, an image is formed on the sheet S.

  As shown in FIG. 2, the line head 51 includes a first recording head 511a, a second recording head 511b, and a third recording head 511c. The first recording head 511a, the second recording head 511b, and the third recording head 511c are arranged in a zigzag pattern along the X direction (front-rear direction) orthogonal to the sheet conveying direction A. Note that the X direction (front-rear direction), which is the direction in which the first recording head 511 a, the second recording head 511 b, and the third recording head 511 c are arranged, coincides with the width direction of the transport belt 41. Further, the first recording head 511a, the second recording head 511b, and the third recording head 511c have the same configuration, and hence are collectively referred to as the recording head 511. The recording head 511 ejects ink droplets from the nozzle holes corresponding to the printing position on the sheet S conveyed by the conveying belt 41.

  The sheet S on which ink droplets are ejected from the nozzle holes of the recording head 511 constituting the line head 51 and an image is formed is conveyed by the conveying belt 41 and extends downstream in the sheet conveying direction A of the conveying belt 41. It is sent out to the second conveyance path 12 provided.

  The sheet S sent to the second conveyance path 12 is directed to a sheet discharge port 12A formed on the + Y side (left side) of the apparatus main body 10 by a second conveyance roller pair 121 provided on the second conveyance path 12. And is discharged onto the paper discharge tray 60 from the paper discharge port 12A.

  On the other hand, when the sheet S sent to the second conveyance path 12 is for double-sided printing in which the image forming process on one side is completed, the sheet S is sandwiched between the second conveyance roller pair 121. It is said. In this state, the sheet S is switched back by rotating the second conveying roller pair 121 in the reverse direction. As a result, the sheet S is sent out to the third conveyance path 13. The sheet S sent to the third conveyance path 13 is reversely fed by the third conveyance roller pair 131 provided in the third conveyance path 13, and the front and back are reversed through the registration roller pair 112 and the guide unit 30. In this state, the toner is again supplied onto the first surface 411 of the conveyor belt 41. In this way, the sheet S supplied on the first surface 411 of the conveyance belt 41 with the front and back sides reversed is subjected to image formation processing on the back side by the image forming unit 50 while being conveyed by the conveyance belt 41. The sheet S for which double-sided printing is completed passes through the second conveyance path 12 and is discharged onto the paper discharge tray 60 from the paper discharge port 12A.

[Detailed configuration of sheet conveying device]
Next, the configuration of the sheet conveying apparatus 40 will be described in detail with reference to FIGS. 5 to 10 in addition to FIGS. 1 to 4. FIG. 5 is a perspective view for explaining the configuration of the conveyance belt 41 and the belt guide member 431 of the suction unit 43 provided in the sheet conveyance device 40. FIG. 6 is a perspective view of the state in which the conveyance belt 41 and the belt guide member 431 in FIG. 5 are cut along line VI-VI. FIG. 7 is an enlarged perspective view showing a part of FIG. FIG. 8 is a view of the suction unit 43 provided in the sheet conveying apparatus 40 as viewed from above. FIG. 9 is a diagram for explaining the configuration of the air duct 44A in the air blowing unit 44 provided in the sheet conveying apparatus 40, and is a perspective view in a state cut along the line IX-IX in FIG. FIG. 10 is a view for explaining the configuration of the air duct 44A, and is a perspective view in a state cut along the line XX of FIG.

  The sheet conveying device 40 is disposed so as to face the line head 51 on the −Z side (lower side) of the image forming unit 50. The sheet conveying apparatus 40 conveys the sheet S fed by the registration roller pair 112 and guided and supplied by the guide unit 30 toward the image forming unit 50 in the sheet conveying direction A. The sheet conveyance device 40 includes a conveyance belt 41, a suction unit 43, and a blower unit 44.

  The conveyor belt 41 is an endless belt having a width in the X direction (front-rear direction) and extending in the Y direction (left-right direction). The conveyance belt 41 has a first surface 411 and a second surface 412 opposite to the first surface 411, is disposed to face the image forming unit 50, and the sheet S is placed on the first surface 411. The sheet is conveyed in the sheet conveying direction A. More specifically, the conveyance belt 41 holds the sheet S on the first surface 411 in a predetermined conveyance area facing the line head 51 of the image forming unit 50 and conveys the sheet S in the sheet conveyance direction A. Here, in the conveyor belt 41 which is an endless belt, the first surface 411 is an outer peripheral surface, and the second surface 412 is an inner peripheral surface.

  As shown in FIG. 1, the transport belt 41 is stretched around a first roller 421, a second roller 422, a third roller 423, and a pair of fourth rollers 424. Inside the stretched conveyor belt 41, a suction part 43 is disposed so as to face the second surface 412.

  The first roller 421 is a drive roller that extends along the X direction (front-rear direction) that is the width direction of the transport belt 41, and is disposed downstream of the suction unit 43 in the sheet transport direction A. The first roller 421 is driven to rotate by a motor (not shown) and rotates the conveyor belt 41 in a predetermined rotation direction. As the conveyance belt 41 rotates, the sheet S held on the first surface 411 is conveyed in the sheet conveyance direction A.

  The second roller 422 is a belt speed detection roller that extends in the X direction (front-rear direction), and is disposed upstream of the suction unit 43 in the sheet conveyance direction A. The second roller 422 cooperates with the first roller 421, a region facing the line head 51 on the first surface 411 of the transport belt 41, and a region facing the suction portion 43 on the second surface 412 of the transport belt 41. Are arranged so that the flatness of the is maintained. Here, in the first surface 411 of the transport belt 41, the region facing the line head 51 and the region between the first roller 421 and the second roller 422 is for holding and transporting the sheet S. This is the predetermined transfer area. The second roller 422 rotates following the rotation of the transport belt 41. A pulse plate (not shown) is attached to the second roller 422, and this pulse plate rotates integrally with the second roller 422. By measuring the rotational speed of the pulse plate, the rotational speed of the conveyor belt 41 is detected.

  The third roller 423 is a tension roller extending along the X direction (front-rear direction), and applies tension to the transport belt 41 so that the transport belt 41 does not bend. The third roller 423 rotates following the rotation of the conveyor belt 41. Each of the pair of fourth rollers 424 is a guide roller extending along the X direction (front-rear direction), and guides the conveyor belt 41 so that the conveyor belt 41 passes through the −Z side (lower side) of the suction portion 43. To do. The pair of fourth rollers 424 are driven to rotate in conjunction with the rotation of the conveyance belt 41.

  Further, as shown in FIGS. 5 to 7, the transport belt 41 has a plurality of suction holes 413 (through holes) penetrating in the thickness direction from the first surface 411 to the second surface 412. 5 to 7, a region portion on the −Y side (right side) of the transport belt 41 is notched so that the surface state of the belt guide member 431 in the suction unit 43 described later can be recognized. In the transport belt 41, each of the plurality of suction holes 413 has a long hole shape extending along the Y direction (left-right direction), and is arranged in the Y direction (left-right direction) and the X direction (front-back direction). Has been.

  The suction unit 43 is disposed to face the image forming unit 50 with the conveyance belt 41 interposed therebetween. More specifically, the suction unit 43 faces the second surface 412 inside the conveyance belt 41 stretched by the first roller 421, the second roller 422, the third roller 423, and the pair of fourth rollers 424. Are arranged. The suction unit 43 generates a negative pressure between the sheet S closely contacted with the first surface 411 of the conveyance belt 41 and a conveyance belt 41 by a blower unit 44 described later, whereby the sheet S is transferred to the first of the conveyance belt 41. The surface 411 is closely attached. As a result, the sheet S is held on the first surface 411 of the transport belt 41. The suction unit 43 includes a belt guide member 431, a suction housing 432, a suction device 433, and an exhaust duct 434.

  In the suction portion 43, the belt guide member 431 is disposed opposite to the region between the first roller 421 and the second roller 422 on the second surface 412 of the transport belt 41, and the width direction (X It is a plate-like member having a width dimension substantially the same as the length of (direction). The belt guide member 431 constitutes an upper surface portion of the suction housing 432 and has substantially the same shape as the suction housing 432 when viewed from the + Z side (upper side). The belt guide member 431 guides the circular movement of the transport belt 41 in conjunction with the rotation of the first roller 421 between the first roller 421 and the second roller 422.

  5 to 7, the belt guide member 431 includes a plurality of first grooves 4311A and second grooves 4311B formed on the belt guide surface 4311 opposed to the second surface 412 of the conveyor belt 41. Have. Each first groove 4311 </ b> A corresponds to the suction hole 413 formed in the center in the width direction (X direction) of the transport belt 41, and is in the center in the width direction (X direction) of the belt guide surface 4311 of the belt guide member 431. It is the groove part formed. Each first groove 4311A is a long groove extending between both ends in the Y direction (left-right direction) of the belt guide surface 4311 of the belt guide member 431. In the present embodiment, as shown in FIG. 5, three first grooves 4311A extending in parallel with each other in the Y direction (left-right direction) are arranged in the width direction (X direction).

  Each second groove 4311B corresponds to a suction hole 413 formed on both ends with respect to the center in the width direction (X direction) of the conveyor belt 41, in the width direction of the belt guide surface 4311 in the belt guide member 431 ( (X direction) It is a groove part formed in the both ends with respect to the 1st groove | channel 4311A formed in the center part. Each second groove 4311B is a long groove extending in the Y direction (left-right direction) with a shorter length than the first groove 4311A on the belt guide surface 4311 of the belt guide member 431. In the present embodiment, as shown in FIG. 5, in the belt guide surface 4311 of the belt guide member 431, each region on both end sides with respect to the first groove 4311 </ b> A formed in the center portion in the width direction (X direction) The second grooves 4311B are arranged along the Y direction (left-right direction) and the X direction (front-back direction).

  Further, the belt guide member 431 has a first through hole 4311Aa provided corresponding to each first groove 4311A and a second through hole 4311Ba provided corresponding to each second groove 4311B. The first through hole 4311Aa is a hole that penetrates in the thickness direction of the belt guide member 431 in the first groove 4311A, and is formed at the center in the width direction (X direction) of the transport belt 41 via the first groove 4311A. The suction holes 413 communicated with each other. Further, the second through hole 4311Ba is a hole portion that penetrates in the thickness direction of the belt guide member 431 in the second groove 4311B, and the central portion in the width direction (X direction) of the transport belt 41 via the second groove 4311B. Communicates with suction holes 413 formed on both ends. Here, in the belt guide surface 4311 of the belt guide member 431, the number of second through holes 4311Ba per unit area is set larger than the number of first through holes 4311Aa per unit area. That is, the number of through-holes in the belt guide surface 4311 of the belt guide member 431 is set so that the regions on both end sides are larger than the center portion in the width direction (X direction).

  The suction portion 43 including the belt guide member 431 configured as described above includes the first groove 4311A and the second groove 4311B of the belt guide member 431, the first through hole 4311Aa and the second through hole 4311Ba, and the conveyor belt 41. The suction force is generated by sucking air from the + Z side (upper side) space of the conveyor belt 41 through the suction hole 413. Due to this suction force, an air flow (suction air) toward the suction unit 43 is generated in the space above the transport belt 41. When the sheet S is guided on the conveyance belt 41 by the guide unit 30 and covers a part of the first surface 411 of the conveyance belt 41, a suction force (negative pressure) acts on the sheet S, and the sheet S is conveyed to the conveyance belt 41. The first surface 411 is closely attached.

  Here, as described above, in the belt guide surface 4311 of the belt guide member 431, the number of through holes communicating with the suction holes 413 of the conveyor belt 41 is the first through hole formed in the center in the width direction (X direction). The number of second through holes 4311Ba formed in the region on both end sides is set to be larger than that of 4311Aa. For this reason, the suction force (negative pressure) acting on the sheet S on the first surface 411 of the conveyor belt 41 becomes larger in the region on both end sides than the central portion in the width direction (X direction). As a result, the sheet S can be uniformly adhered in the width direction (X direction) of the transport belt 41.

  In the suction portion 43, the suction housing 432 is a box-shaped housing having an opening on the + Z side (upper side), and the opening on the + Z side (upper side) forms a belt guide member that constitutes the upper surface portion of the suction housing 432. It is arranged on the −Z side (lower side) of the conveyor belt 41 so as to be covered by the belt 431. The suction housing 432 defines a suction space 432A in cooperation with the belt guide member 431 constituting the upper surface portion thereof. That is, the space surrounded by the suction housing 432 and the belt guide member 431 becomes the suction space 432A. The suction space 432A communicates with the suction hole 413 of the transport belt 41 through the first groove 4311A and the second groove 4311B of the belt guide member 431, the first through hole 4311Aa, and the second through hole 4311Ba.

  The suction housing 432 will be described in detail with reference to FIG. 8. The suction housing 432 includes a rectangular plate-shaped bottom wall portion 4321, and a side wall portion 4322 erected on the outer peripheral edge of the bottom wall portion 4321. And a partition wall portion 4323 that stands on the bottom wall portion 4321 and divides the suction space 432A into a plurality of regions. A belt guide member 431 is disposed at the upper end portion of the side wall portion 4322 in the suction housing 432 so as to face the bottom wall portion 4321. In the present embodiment, the suction space 432A is partitioned by the partition wall portion 4323 into a first space 432Aa, a second space 432Ab, a third space 432Ac, and a fourth space 432Ad.

  The first space 432Aa is an upstream region in the sheet conveyance direction A in the suction space 432A, extends between both end portions in the width direction (X direction) of the suction housing 432, and + Y side in the center portion in the width direction (X direction). It is a space that extends to the left. The second space 432Ab is an area located downstream of the first space 432Aa in the sheet conveying direction A in the suction space 432A, and is located with respect to the first space 432Aa at the center in the width direction (X direction) of the suction housing 432. And a space adjacent to the downstream side in the sheet conveying direction A.

  The third space 432Ac is an area located in the suction space 432A on the downstream side in the sheet conveying direction A with respect to the first space 432Aa and on the + X side (rear side) with respect to the second space 432Ab. Specifically, the third space 432Ac is adjacent to the first space 432Aa on the downstream side in the sheet conveying direction A on the + X side (rear side) in the width direction (X direction) of the suction housing 432, and This is a space adjacent to the + X side (rear side) with respect to the two spaces 432Ab. In addition, the fourth space 432Ad is an area located in the suction space 432A on the downstream side in the sheet conveyance direction A with respect to the first space 432Aa and on the −X side (front side) with respect to the second space 432Ab. Specifically, the fourth space 432Ad is adjacent to the first space 432Aa on the downstream side in the sheet conveying direction A on the −X side (front side) in the width direction (X direction) of the suction housing 432, and This is a space adjacent to the −X side (front side) with respect to the two spaces 432Ab.

  Further, in the bottom wall portion 4321 of the suction housing 432, a first opening 432Ba is formed in the first space 432Aa defined by the partition wall portion 4323, and a second opening 432Bb is formed in the second space 432Ab. Thus, a third opening 432Bc is formed in the third space 432Ac, and a fourth opening 432Bd is formed in the fourth space 432Ad. The first suction device 433A is disposed corresponding to the first opening 432Ba on the −Z side (lower side) of the bottom wall portion 4321 of the suction housing 432, and the second corresponding to the second opening 432Bb. A suction device 433B is disposed, a third suction device 433C is disposed corresponding to the third opening 432Bc, and a fourth suction device 433D is disposed corresponding to the fourth opening 432Bd. Each of the first suction device 433A, the second suction device 433B, the third suction device 433C, and the fourth suction device 433D includes a first opening 432Ba, a second opening 432Bb, a third opening 432Bc, and a fourth opening. It is connected to the suction space 432A via each of the portions 432Bd. Further, as shown in FIG. 1, an exhaust duct 434 is connected to each of the first suction device 433A, the second suction device 433B, the third suction device 433C, and the fourth suction device 433D. The exhaust duct 434 is connected to an exhaust port (not shown) provided in the apparatus main body 10.

  Each of the first suction device 433A, the second suction device 433B, the third suction device 433C, and the fourth suction device 433D is a suction fan, but is not limited to the suction fan, for example, a vacuum pump. Also good. The first suction device 433A, the second suction device 433B, the third suction device 433C, and the fourth suction device 433D are driven, so that the first space 432Aa, the second space 432Ab, and the third space 432Ac in the suction housing 432 are driven. A negative pressure is generated in each of the fourth spaces 432Ad. Due to this negative pressure, a suction force is generated in the first groove 4311A and the second groove 4311B via the first through hole 4311Aa and the second through hole 4311Ba of the belt guide member 431, and the first groove 4311A and the second groove 4311B. A suction force is generated in the suction hole 413 of the transport belt 41 via the. As a result, air from the + Z side (upper side) space of the conveyor belt 41 is sucked into each of the first space 432Aa, the second space 432Ab, the third space 432Ac, and the fourth space 432Ad in the suction housing 432.

  The air sucked into each of the first space 432Aa, the second space 432Ab, the third space 432Ac, and the fourth space 432Ad in the suction housing 432 is the first suction device 433A, the second suction device 433B, and the third suction device 433C. And it exhausts via the exhaust duct 434 connected to each of 4th suction device 433D. Then, when the sheet S is guided on the conveyance belt 41 by the guide unit 30 to cover a part of the first surface 411 of the conveyance belt 41 and close some of the plurality of suction holes 413, the sheet S is blocked. A suction force (negative pressure) acts on the sheet S from the suction holes 413 so that the sheet S is brought into close contact with the first surface 411 of the transport belt 41. Here, the suction space 432A in the suction housing 432 is partitioned into a first space 432Aa, a second space 432Ab, a third space 432Ac, and a fourth space 432Ad by the partition wall portion 4323, and corresponds to each partitioned space. Since the air is sucked by the arranged first suction device 433A, second suction device 433B, third suction device 433C and fourth suction device 433D, the entire surface of the sheet S is made uniform on the first surface 411 of the conveyor belt 41. It can be adhered.

  Next, the air blowing unit 44 provided in the sheet conveying apparatus 40 will be described mainly with reference to FIGS. 1, 9, and 10. The air blowing unit 44 blows wind toward the sheet S on the upstream side in the sheet conveying direction A of the image forming unit 50 to bring the sheet S into close contact with the first surface 411 of the conveying belt 41. The suction unit 43 causes the sheet S to adhere to the first surface 411 of the conveyance belt 41 by generating a negative pressure between the sheet S and the conveyance belt 41 that is adhered to the first surface 411 by the blower unit 44. Let The blower unit 44 includes a blower duct 44A and a blower 44B.

  The air duct 44 </ b> A is in the predetermined conveyance area between the first roller 421 and the second roller 422 on the first surface 411 of the conveyance belt 41, and is upstream of the image forming unit 50 in the sheet conveyance direction A. It is the duct arrange | positioned facing the area | region of the side. The air duct 44A includes a duct body 441 and a wind direction adjusting unit 442.

  The duct main body 441 is a box-shaped cylindrical body that forms a main body portion of the air duct 44A, extends along the width direction (X direction) of the transport belt 41, and forms an air blowing space 441A that serves as an air blowing passage. . The duct body 441 opens toward the air introduction port 4411 formed at the −X side (front side) end portion in the X direction (front-rear direction) which is the extending direction, and the first surface 411 of the transport belt 41, And an outlet 4412 for blowing wind toward the first surface 411. The air outlet 4412 is an opening that is opened between both ends in the width direction (X direction) of the conveyor belt 41.

  The air duct 44 </ b> A blows out air introduced from the air introduction port 4411 into the air blowing space 411 </ b> A of the duct body 441 toward the first surface 411 of the transport belt 41 from the air outlet 4412. In the present embodiment, the air introduced from the air introduction port 4411 of the duct body 441 into the blowing space 411A is air generated by the blower 44B. That is, the air duct 44 </ b> A blows out air, which is generated by the air blower 44 </ b> B and introduced into the air blowing space 411 </ b> A of the duct main body 441 from the air outlet 4412 toward the first surface 411 of the transport belt 41.

  Note that the exhaust duct 434 of the suction portion 43 may be connected to the air introduction port 4411 so that air exhausted through the exhaust duct 434 may be introduced from the air introduction port 4411 into the air blowing space 411A of the duct main body 441. . In this case, the air duct 44 </ b> A blows out the air exhausted from the exhaust duct 434 and introduced into the air blowing space 411 </ b> A of the duct main body 441 from the air inlet 4411 toward the first surface 411 of the transport belt 41. . Thereby, the air exhausted from the exhaust duct 434 can be used effectively without installing the blower 44B separately. However, in this case, the blowing force of the air blown from the outlet 4412 of the blower duct 44 </ b> A to the sheet S varies depending on the amount of air discharged from the exhaust duct 434. The amount of air exhausted from the exhaust duct 434 decreases as the ratio of the first surface 411 of the conveyor belt 41 covered with the sheet S increases. That is, the blowing force of the air blown from the blower outlet 4412 of the blower duct 44 </ b> A to the sheet S is strong until immediately before the leading end of the sheet S conveyed by the conveying belt 41 reaches the image forming unit 50, and then decreases. Will do.

  In the sheet conveying apparatus 40 including the air blowing unit 44 having the air duct 44 </ b> A, the sheet S is brought into close contact with the conveying belt 41 by the wind blown from the outlet 4412 of the duct main body 441 toward the first surface 411 of the conveying belt 41. Meanwhile, the sheet S is brought into close contact with the conveyance belt 41 by the negative pressure generated by the suction unit 43. In other words, the air blown from the air outlet 4412 of the air duct 44A can assist the suction of the sheet S to the transport belt 41 by the suction portion 43. For this reason, even when the leading edge of the sheet S guided by the guide section 30 and supplied to the conveying belt 41 is deformed, such as undulation, the leading edge of the sheet S and the conveying belt 41 It is possible to prevent a gap from occurring between them, and to suppress the occurrence of poor adhesion of the sheet S to the conveyance belt 41. Accordingly, the sheet conveying apparatus 40 having excellent conveying characteristics of the sheet S by the conveying belt 41 can be obtained.

  In addition, paper dust may adhere to the leading end of the sheet S. When the sheet S is transported by the transport belt 41 with the paper dust adhered to the leading end in this manner, the paper dust of the image forming unit 50 arranged to face the first surface 411 of the transport belt 41 is used. There is a possibility of adhering to the recording head 511 and clogging of the nozzle holes of the recording head 511. On the other hand, in the sheet conveying apparatus 40 according to the present embodiment, the wind is blown out from the outlet 4412 of the air duct 44A toward the first surface 411 of the conveying belt 41, so that the wind adheres to the leading end portion of the sheet S. Paper dust can be removed. For this reason, it is possible to suppress the adhesion of paper dust to the recording head 511 of the image forming unit 50 as much as possible.

  The paper dust removed from the front end portion of the sheet S is scattered from the center toward the end portion on the upper surface of the sheet S. For this reason, adhesion of paper dust to the conveyor belt 41 is suppressed as much as possible. Even if paper dust adheres to the conveyor belt 41, the paper dust is caused by the flow of air blown from the outlet 4412 of the air duct 44A, and the suction holes 413 of the conveyor belt 41 and the belt support member 431 first. It enters the first space 432Aa of the suction housing 432 through the first through hole 4311Aa and the second through hole 4311Ba, and is collected by a filter attached to the exhaust duct 434 connected to the first suction device 433A. .

  Further, in the sheet conveying apparatus 40 according to the present embodiment, the suction unit 43 is configured to bring the sheet S into close contact with the conveying belt 41 by sucking air through the suction holes 413 of the conveying belt 41. On the other hand, as described above, the air blown from the outlet 4412 of the blower duct 44A toward the conveyance belt 41 can assist the adhesion of the sheet S to the conveyance belt 41 by the suction portion 43. For this reason, the selection range of the air suction capability in the suction unit 43 can be widened. For example, a versatile suction fan having a relatively low air suction capability (low maximum static pressure) is used as the first suction unit 43. Thru | or 4th suction apparatus 433A, 433B, 433C, 433D can be used.

  The air duct 44 </ b> A includes a wind direction adjusting unit 442. The air direction adjusting portion 442 is disposed in the air blowing space 441A of the duct body 441 so that the air blown from the air outlet 4412 spreads from the central portion in the width direction (X direction) of the conveyor belt 41 toward both ends. Adjust the wind direction. Specifically, the air direction adjusting unit 442 includes a first air direction adjusting plate 4421 and a second air direction adjusting plate that divide the air outlet 4412 of the duct body 441 into a plurality of regions arranged in the width direction (X direction) of the transport belt 41. 4422 is configured.

  In the present embodiment, as shown in FIGS. 9 and 10, a plurality of first air direction adjustment plates 4421 are arranged in the width direction (X Direction), and a plurality of second wind direction adjusting plates 4422 are arranged along the width direction (X direction) on the + X side (rear side) with respect to the central portion of the conveyance belt 41 in the width direction (X direction). It is installed.

  Each of the plurality of first wind direction adjusting plates 4421 is inclined toward the −X side (front side) end portion from the center portion in the width direction (X direction) of the conveyor belt 41, and on the lower side approaching the first surface 411 ( -Z side). Each of the plurality of second wind direction adjusting plates 4422 is inclined toward the + X side (rear side) end portion from the center portion in the width direction (X direction) of the conveyor belt 41, and on the lower side approaching the first surface 411 ( -Z side). Note that the end wall portion 441B that defines the + X side (rear side) end portion in the X direction (front-rear direction) in the duct body 441 is inclined in the same manner as the second air direction adjusting plate 4422.

  In the air duct 44A including the air direction adjusting unit 442 configured to include the first air direction adjusting plate 4421 and the second air direction adjusting plate 4422, the air is introduced into the air blowing space 411A of the duct main body 441 from the air introduction port 4411, and is on the −X side. The air flowing along the direction of the arrow B1 from the (front side) to the + X side (rear side) is first on the −X side (front side) with respect to the central portion in the width direction (X direction) of the conveyor belt 41. Adjusted in the direction of arrow B2 along the wind direction adjusting plate 4421 and adjusted in the direction of arrow B3 along the second wind direction adjusting plate 4422 on the + X side (rear side) with respect to the central portion in the width direction (X direction) of the conveyor belt 41 Is done. And, from the area defined by the first air direction adjusting plate 4421 of the outlet 4412, the wind spreading from the center in the width direction (X direction) of the conveyor belt 41 toward the −X side (front side) end is blown out. From the area defined by the second air direction adjusting plate 4422 of the air outlet 4412, the wind spreading from the central portion in the width direction (X direction) of the conveyor belt 41 toward the + X side (rear side) end portion is blown out.

  As described above, the wind direction adjusting unit is configured so that the wind blown from the outlet 4412 of the duct main body 441 toward the transport belt 41 spreads from the center in the width direction (X direction) of the transport belt 41 toward both ends. The wind direction is adjusted by 442. Thereby, the sheet S can be uniformly adhered in the width direction (X direction) of the transport belt 41. Therefore, the conveyance characteristics of the sheet S by the conveyance belt 41 can be further improved.

  Further, the wind direction adjusting unit 442 includes a shielding plate 4423. As shown in FIGS. 9 and 10, the shielding plate 4423 includes a first wind direction adjusting plate 4421 closest to the center in the width direction (X direction) among the plurality of first wind direction adjusting plates 4421 and a plurality of second wind directions. It arrange | positions so that the + Z side (upper side) edge part with the 2nd wind direction adjustment board 4422 near the center part of the width direction (X direction) of the adjustment boards 4422 may be connected. The shielding plate 4423 functions as a shielding unit that shields the blowing of wind from the outlet 4412 of the air duct 44A toward the center in the width direction (X direction) of the conveyor belt 41. Thereby, the wind blown out from the blower outlet 4412 of the blower duct 44 </ b> A spreads more reliably from the center in the width direction (X direction) of the transport belt 41 toward both ends. For this reason, the sheet S can be uniformly adhered in the width direction (X direction) of the transport belt 41.

  In addition, since the image forming apparatus 1 of the present embodiment includes the sheet conveying device 40 that is excellent in the conveying characteristics of the sheet S by the conveying belt 41, the conveyance failure of the sheet S is included in the image formed by the image forming unit 50. Occurrence of image defects due to the image is suppressed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various deformation | transformation embodiment can be taken.

  (1) In the above embodiment, the suction force is generated by sucking air through the suction holes 413 of the transport belt 41 as the suction portion 43 for bringing the sheet S into close contact with the first surface 411 of the transport belt 41. Although the structure to make it demonstrated was demonstrated, this invention is not limited to such a structure. For example, the suction unit 43 may include a conductive electrode pair provided on the transport belt 41. In this case, the suction unit 43 electrostatically adheres the sheet S to the first surface 411 of the transport belt 41 by generating an electrostatic suction force between the sheet S and the transport belt 41. In such a configuration in which the sheet S is electrostatically adhered, it is not necessary to provide the suction hole 413 in the transport belt 41.

  (2) In the above embodiment, the ink jet recording apparatus has been described as the image forming apparatus 1. However, the image forming apparatus 1 of the present invention is not limited to the ink jet recording apparatus. The image forming apparatus 1 of the present invention may be an apparatus provided with the sheet conveying apparatus 40 including the conveying belt 41, and various types such as a laser beam type, a thermal type, a wire dot type, etc. can be used other than the ink jet type. The apparatus can be an image forming system (recording system).

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Apparatus main body 20 Paper feed part 30 Guide part 40 Sheet conveying apparatus 41 Conveying belt 411 1st surface 412 2nd surface 413 Suction hole (through-hole)
43 Suction Unit 431 Belt Guide Member 432 Suction Housing 433A First Suction Device 433B Second Suction Device 433C Third Suction Device 433D Fourth Suction Device 434 Exhaust Duct 44 Blower Unit 44A Blower Duct 44B Blower 441 Duct Body 441A Blower Space 441B End Wall portion 4411 Air inlet port 4412 Air outlet 442 Air direction adjusting portion 4421 First air direction adjusting plate 4422 Second air direction adjusting plate 4423 Shielding plate (shielding portion)
50 Image forming unit (processing unit)

Claims (6)

A sheet conveying apparatus that conveys a sheet to a predetermined processing unit,
A conveyance belt having a first surface and a second surface opposite to the first surface, disposed opposite the processing unit, and conveys the sheet in a predetermined conveyance direction on the first surface. When,
A blower unit that blows air toward the sheet on the upstream side in the conveyance direction of the processing unit, and causes the sheet to adhere to the first surface of the conveyance belt;
By generating a negative pressure between the conveying belt and the sheet that is disposed to face the processing unit and the conveying belt and is in close contact with the first surface by the blower unit, the sheet is A sheet conveying device comprising: a suction unit that is in close contact with the first surface of the conveying belt. The blower unit has a blower duct that includes a blowout port that extends in the width direction of the conveyor belt and blows air toward the sheet.
The sheet conveying device according to claim 1, wherein the air duct includes a wind direction adjusting unit that spreads the air blown from the air outlet toward the both ends from the central portion in the width direction. The wind direction adjusting unit includes a plurality of wind direction adjusting plates arranged in parallel in the width direction, which divides the air outlet into a plurality of regions arranged in the width direction.
The sheet conveying device according to claim 2, wherein the plurality of wind direction adjusting plates are inclined toward the end from the central portion in the width direction and extend toward a lower side approaching the first surface.   The sheet conveying apparatus according to claim 2, wherein the wind direction adjusting unit includes a shielding unit that shields the blowing of wind from the air outlet toward the central portion in the width direction. The conveyor belt has a plurality of through holes penetrating from the first surface to the second surface,
The suction portion is disposed to face the second surface of the transport belt, and generates the negative pressure by sucking air through the through hole, so that the sheet is moved to the first surface of the transport belt. The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is in close contact with the surface. A sheet conveying device according to any one of claims 1 to 5,
An image forming apparatus comprising: an image forming unit as the processing unit that forms an image on a sheet conveyed by the conveying belt of the sheet conveying device.

Images